遍历所有级别的字典

Question

我在字典中有一个数据结构，如下所示：

- device
   - type
   - isActive
   - Data
      - Manufacturer 
      - Build Date
      - Power
      ...
   - Example

现在，如果我创建一个 For 循环，它只会显示第一级的值，这意味着

type, isActive, Data, Example


for (key, value) in value {

}

以下所有数据（例如构建日期或电源）都丢失了 - 我怎么也能通过这些级别感到恼火？

Answer 1

假设您有类型为 [String:Any] 的字典，将其展平的函数将类似于：

    func flatten(_ obj:[String:Any]) -> [String:Any] {
        var result = [String:Any]()
        for (key, val) in obj {
            if let v = val as? [String:Any] {
                result = result.merging(flatten(v), uniquingKeysWith: {
                    $1
                })
            }
            //I also included initial value of internal dictionary
            /if you don't need initial value put next line in 'else'
            result[key] = val 
        }
        return result
    }

要使用它：

    let d:[String:Any] = [
        "test1":1,
        "test2":2,
        "test3":[
            "test3.1":31,
            "test3.2":32
        ]
    ]
    let res = flatten(d)
    print(res)

[“test2”：2，“test3.2”：32，“test3.1”：31，“test1”：1，“test3”： [“test3.2”：32，“test3.1”：31]]

注意：字典不是排序结构

Answer 2

您正在处理Recursion 问题。

---

你可以逐级走字典：

func walk(dictionary: [String: Any]) {
    for (key, value) in dictionary {
        print("\(key): \(value)")
        if let value = value as? [String: Any] {
            walk(dictionary: value)
        }
    }
}

您可以将[String: Any] 类型更改为您的字典类型（NSDictionary 等）

Answer 3

正如 Tomas 所说，这可以通过递归来解决。他的“walk”函数只是在不同的行上打印值，但没有键，也没有格式化。这是使用您概述的结构记录嵌套字典的代码：

//Define the keys we use in our example
enum keys: String {
    case device
    case type
    case isActive
    case Data
    case Manufacturer
    case BuildDate
    case Power
    case Example
    }

//Create a sample dictionary using those keys and some random values
let dict = [keys.device.rawValue:
                [keys.type.rawValue: "appliance",
                 keys.isActive.rawValue: true,
                 keys.Data.rawValue:
                    [keys.Manufacturer.rawValue: "GE",
                     keys.BuildDate.rawValue: "12/23/96",
                     keys.Power.rawValue: 23,
                    ],
                 keys.Example.rawValue: "Foo"
                ]
]

//Create an extension of Dictionary for dictionaries with String Keys.
extension Dictionary where Key == String {
    
    //Define a function to recursively build a description of our dictionary
    private func descriptionOfDict(_ aDict: [String: Any], level: Int = 0) -> String {
        var output = ""
        var indent: String = ""
        if level > 0 {
            output += "\n"
            for _ in 1...level {
                indent += "   "
            }
        }
        for (key,value) in aDict {
            output += indent + key + ": "
            if let subDict = value as? [String: Any] {
                //If the value for this key is another dictionary, log that recursively
                output +=  descriptionOfDict(subDict, level: level+1)
            } else {
                if let aString = value as? String {
                    output += "\"" +  aString + "\"\n"
                }  else {
                    output += String(describing: value) + "\n"
                }
            }
        }
        return output
    }
    
    //Add a description property for dictionaries
    var description: String  {
        return descriptionOfDict(self)
    }
}


print(dict.description)

输出：

device: 
   isActive: true
   Data: 
      Manufacturer: "GE"
      Power: 23
      BuildDate: "12/23/96"
   Example: "Foo"
   type: "appliance"

编辑：

上面定义了String 属性description，当您打印[String:Any] 字典时会更改输出。如果您不希望这样，请将属性 description 重命名为 dictDescription 之类的其他名称